Bijeesh Kozhikkodan Veettil

Recent trends in annual snowline variations in the northern wet outer tropics: case studies from southern Cordillera Blanca, Peru

This paper describes the changes in the annual maximum snowlines of a selected set of mountain glaciers at the southern end of the Cordillera Blanca between 1984 and 2015 using satellite images. Furthermore, we analysed the existing glacier records in the Cordillera Blanca since the last glacial maximum to understand the evolution of glaciers in this region over a few centuries. There was a rise in the snowline altitude of glaciers in this region since the late 1990s with a few small glacier advances. Historical to the present El Niño-Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) records were also analysed to understand whether there was a teleconnection between the glacier fluctuations in the region and the phase changes of ENSO and PDO. We also assessed the variations in three important climatic parameters that influence the glacier retreat—temperature, precipitation, and relative humidity—over a few decades. We calculated the anomalies as well as the seasonal changes in these variables since the mid-twentieth century. There was an increase in temperature during this period, and the decrease in precipitation was not so prominent compared with the temperature rise. There was an exceptionally higher increase in relative humidity since the early 2000s, which is relatively higher than that expected due to the observed rate of warming, and this increase in humidity is believed to be the reason behind the unprecedented rise in the snowline altitudes since the beginning of the twenty-first century.

Variations in annual snowline and area of an ice-covered stratovolcano in the Cordillera Ampato, Peru, using remote sensing data (1986–2014)

This research focuses on the recent variations in the annual snowline and the total glaciated area of the Nevado Coropuna in the Cordillera Ampato, Peru. Maximum snowline altitude towards the end of dry season is taken as a representative of the equilibrium line altitude of the year, which is an indirect measurement of the annual mass balance. We used Landsat and IRS LISS3 images during the last 30 years due to its better temporal coverage of the study site. It is found that there was a decrease of 26.92% of the glaciated area during 1986–2014. We calculated the anomalies in precipitation and temperature in this region and also tried to correlate the changes in glacier parameters with the combined influence of El Niño – Southern Oscillation (ENSO) and pacific decadal oscillation (PDO). It is concluded that the snowline of Nevado Coropuna has been fluctuated during ENSO, and maximum fluctuations were observed when ENSO and PDO were in phase.

Recent Changes Occurred in the Terminus of the Debris- covered Bilafond Glacier in the Karakoram Himalayas Using Remotely Sensed Images and Digital Elevation Models (1978-2011)

Recent changes occurred in terminus of the debris-covered Bilafond Glacier in the Karakoram Range in the Himalayas, Northern Pakistan was investigated in this research. Landsat MSS, TM and ETM+ images were used for this study. Digital elevation models derived from ASTER GDEM and SRTM were also utilized. Visible, infrared and thermal infrared channels were utilized in order to get accurate glacier change maps. Three methods were tried to map this debris-covered glacier in this research. The glacier has been mapped successfully and the changes in the glacier terminus from 1978 to 2011 have been calculated. Manual, semi-automatic and thermal methods were found to give similar results. It was found that the glacier has undergone serious ablation during this period despite of the fact that many of the larger glaciers in the Hindu Kush and Karakoram mountain regions in the Upper Indus Basin were reported to be expanding. The terminus has been moved back about 600 meters during this period and there was an abrupt change in the glacier terminus during 1990–2002. We propose that debris thickness is not the only factor that influences the glacier ablation but the altitude of the debris-covered glacier as well. Many glaciers in the Karakoram region reported to be expanding were having higher altitudes compared to the study area.

Influence of ENSO and PDO on mountain glaciers in the outer tropics: case studies in Bolivia

This paper emphasize on the observational investigation of an ice-covered volcano and two glaciated mountains in the Central Andes from 1984 to 2011. Annual snowlines of the Nevado Sajama in the Cordillera Occidental and the Nevado Cololo and the Nevado Huanacuni in the Cordillera Apolobamba in Bolivia were calculated using remote sensing data. Landsat TM, Landsat ETM+, and LISS-III images taken during the end of dry season were used in this study. Changes in the highest annual snowline during May–September is used an indirect measure of the changes in the equilibrium line altitude of the glaciers in the outer tropics. We tried to understand the combined influence of the El Niño-Southern Oscillation and the Pacific Decadal Oscillation on the variations in the annual snowline altitude of the selected glaciers. Meteorological data in the form of gridded datasets were used for calculating the anomalies in precipitation and temperature during the study period. It is found that the glaciated areas were fluctuated with the occurrence of warm and cold phase of ENSO but the magnitude of the influence of ENSO is observed to be controlled by the phase changes of PDO. Snowline of the Nevado Sajama fluctuated heavily when cold and warm phases of ENSO occur during the cold and warm regimes of PDO, respectively. Nevado Cololo and Nevado Huanacuni are showing a continuous retreating trend during the same period. This clearly indicates that the changes in the Pacific SST patterns have more influence on glaciers in the Cordillera Occidental compared with those in the Cordillera Oriental of the Bolivian Andes.

Study of 40-year glacier retreat in the northern region of the Cordillera Vilcanota, Peru, using satellite images: preliminary results

ABSTRACT In this article, the possibility of using a Landsat image series to calculate the decadal changes in the area of mountain glaciers in the eastern cordillera of Peru is explored. In the pilot study site, changes in the glacier area at different elevation ranges to understand the altitudinal gradients and the directional properties of glacier retreat during the period 1975–2015 were calculated. This approach can be used in the entire tropical Andes, particularly in the outer tropics, depending on the availability of cloud-free images during the dry season. Similar to other regions in the tropical Andes, glaciers situated below 5000 m a.s.l. have lost nearly 81% of the initial area. It is observed that those glaciers directed towards north-east and east shows higher retreat and this may influence the glacier-fed rivers in the Amazon Basin. Future research will estimate the glacier variations in the entire eastern cordilleras and the corresponding changes in the water discharge volume in the Amazon Basin.

Recent variations of supraglacial lakes on the Baltoro Glacier in the central Karakoram Himalaya and its possible teleconnections with the pacific decadal oscillation

This study discusses the formation and variations of supraglacial lakes on the Baltoro glacier system in the central Karakoram Himalaya during the last four decades. We mapped supraglacial lakes on the Baltoro Glacier from 1978 to 2014 using Landsat MSS, TM, ETM + and LCDM images. Most of the glacial lakes were formed or expanded during the late 1970s–2008. After 2008, the total number and the area of glacial lakes were found to be lesser compared to previous years. We tried to find any teleconnections exists between the glacial lake changes in this region and the pacific decadal oscillation (PDO), which entered its prolonged warm regime in the late 1970s and again to its cold regime in 2008, based on observational investigation. The decrease in the number and area of the supraglacial lakes after 2008 is hypothesised to be linked with the recent cold phase of PDO.

Un análisis comparativo del comportamiento diferencial de los glaciares en los Andes Tropicales usando teledetección

En este trabajo de investigacion, se analizo el comportamiento de los glaciares de los Andes Tropicales en un clima cambiante; para esto se emplearon imagenes satelitales multiespectrales de diversas fuentes en conjunto con datos meteorologicos. El estudio se enfoco en glaciares representativos de cuatro zonas climaticas diferentes, a saber: tropicos interiores, tropicos exteriores humedos del norte, tropicos exteriores humedos del sur y tropicos exteriores secos. Se calcularon los cambios en la linea de nieve maxima anual para el periodo de 1985―2015, y tambien los cambios decenales en el area entre 1975 y 2015. Ademas, se analizo la tasa de retroceso de los glaciares durante la ocurrencia de El Nino―Oscilacion del Sur y la Oscilacion Decenal del Pacifico. Se observo que los glaciares tanto de los tropicos interiores como de los tropicos exteriores se sometieron a retroceso durante todo el periodo de estudio, con enfasis entre 1975 y 1997, lapso coincidente con el periodo de calentamiento del Pacifico. Se observaron variaciones excepcionales en la altitud de la linea de nieve cuando se produce un evento de El Nino durante la fase calida de la Oscilacion Decenal del Pacifico. Se observo que no hay senales significativas del hiato reciente en el calentamiento global, excepto en los tropicos exteriores secos, localizados cerca de la region subtropical.

Urban heat island development during the last two decades in Porto Alegre, Brazil and its monitoring

This paper describes the development of urban heat island during the last two decades in Porto Alegre, Brazil. Landsat TM images were used for this study and image processing steps were done using MATLAB and Erdas Imagine software packages for the successful monitoring of this urban phenomenon. It is found that there was a significant increase in the surface mean temperature and land use during this period. Reforested area showed significant decrease in land surface temperature.